This invention relates to heterocyclic styryl compounds and/or oligomers and copolymers thereof. More specifically the invention relates to furfural capped polystyryl pyridine oligomers and/or monomers.
The reaction of methylpyridines with aromatic or heterocyclic aldehydes to form stilbazole bonds is known from Berichte 23 pages 2693 and 2697 (1890). The first use of this chemistry with di- or trifunctional materials to intentionally produce polymeric materials (polystyrylpyridines-PSP) is known from U.S. Pat. Nos. 3,994,862 and 4,163,740. This chemistry produces a very thermally stable polymer (PSP) but suffers from several drawbacks, which include: (1) excessively high temperature of polymerization (&gt;200.degree. C.) (2) long cure cycles (&gt;4 hrs) and (3) production of volatiles during the cure. Volatile production during polymerization invariably leads to the formation of voids which decrease the mechanical integrity of the final polymer. The PSP chemistry has been modified to incorporate hydroxybenzaldehyde as is known from U.S. Pat. Nos. 4,515,938 and 4,525,573. These phenolic modifications address problems (1) and (2) by decreasing somewhat the time and temperature necessary for final curing of the resin but failed to achieve the processability needed for many applications (cure temperatures &lt;180.degree. C.; cure times &lt;1 hr).
The PSP backbone can be derivatized by reaction of 2-methyl-5-vinylpyridine to form an alkenyl end cap which can be homopolymerized or copolymerized via an addition cure as is known from U.S. Pat. Nos. 4,362,867; 4,471,107 and 4,526,925. The use of isopropenylphenol as an alkenyl end cap for PSP to produce a polymer which can be copolymerized with bismaleimide compounds is known from U.S. Pat. No. 4,500,690. Both polymers give good overall thermal properties, and cure at low temperatures but the vinyl pyridine or isopropenylphenol are not available in commercial quantities.
The use of furan containing derivatives to terminate non-styryl oligomers is known from U.S. Pat. Nos. 3,904,584; 3,905,941; 3,927,027; and 3,951,902. These patents show that a furanyl capped molecule when reacted with an ethylenically unsaturated molecule reacts via a Diels-Alder reaction to produce a polymer containing 2,2,1-oxobicyclo segments. By heating this polymeric system, the bicyclo segments rearrange with elimination of water to form aromatic rings.